In order to keep competitiveness of a third generation mobile communication system in the communication field, provide users with more individualized mobile communication services with higher rate and lower time delay, and reduce operation cost of operators, the 3rd Generation Partnership Project (3GPP) standard group is committed to research on an Evolved Packet System (EPS).
When two terminals communicate through an EPS network, the two terminals may need to establish bearing with the EPS respectively. However, allowing for rapid development of intelligent terminals and various mobile Internet services, discovery of friends nearby and communication with the nearby friends may need to be supported for many services, so Proximity-based Services (ProSe) are spawned. A terminal supporting the ProSe function can communicate through a specific resource authorized by the network. A communication path for conducting this type of communication may not involve a core network. Such a communication mode reduces circuitry of a data route on one hand, and reduces a network data load on the other hand.
FIG. 1 is a structure diagram of main network elements after a ProSe function is introduced according to the related ProSe technology. As shown in FIG. 1, after the ProSe function is introduced, some network elements and interfaces are added in the network to support the ProSe function.
After obtaining authorization from the network, a terminal A and a terminal B supporting the ProSe function may discover and communicate with each other.
A functional entity named ProSe Function is introduced for supporting the ProSe. The ProSe Function mainly completes authorization and matching for a piece of User Equipment (UE) to discover or be discovered. In a part of solutions, this network element also is in charge of mutual discovery between two pieces of protocol UEs.
An Evolved Universal Terrestrial Radio Access Network (EUTRAN) provides a ProSe terminal with underlying access and necessary discovery and communication resources.
An Evolved Packet Core Network (EPC) may include: a Mobility Management Entity (MME) and a Serving Gateway (SGW)/Packet Data Network Gateway (PGW). These network elements provide the underlying access for the terminal to access the ProSe Function.
A Home Subscriber Server (HSS) including all functions of a Home Location Register (HLR) is a permanent storage location for subscription data of the user and is located in a home network subscribed by the user. After the ProSe is introduced, the network element needs to store ProSe-related subscription data.
A Secure User Plane Location Platform (SLP) is arranged to help discover an adjacent terminal.
A ProSe application server is arranged to map a user application layer Identifier (ID) and a user ID of a user in the 3GPP network.
The terminal supporting the ProSe may discover other terminals around. An open discovery mode or a restrained discovery mode may be set. In the open discovery mode, a terminal has no need to set authorization for other terminals, and can be discovered by the other terminals that can hear announcement of the terminal. However, in the restrained discovery mode, the terminal may set a specific friend list, and only a specific friend in the specific friend list can monitor or identify the terminal, so that the privacy of discovery and communication between the terminals can be ensured. In order to realize the restrained discovery mode, the ProSe application server is in charge of maintaining the friend list of the ProSe.
FIG. 2 is a schematic diagram of a friend discovery process of a terminal in the restrained discovery mode according to the related ProSe discovery technology. As shown in FIG. 2, the terminal may complete the friend discovery process through the authorization of the ProSe application server. The process may include the following acts S202 to S230.
At act S202, an announcing terminal (namely a terminal hoping to be discovered) obtains from an application server a restrained ProSe application identifier (the identifier may be allocated by the ProSe application server) of the announcing terminal.
At act S204, the announcing terminal sends a discovery request to a home ProSe functional entity of the announcing terminal. The discovery request may carry parameters such as the restrained ProSe application identifier and UE ID of the announcing terminal.
At act S206, if the ProSe functional entity does not have context of the UE, it may be needed to initiate an authorization process to the HSS, so as to obtain the ProSe-related subscription data of the user. If the terminal is permitted to perform a discovery process, the subsequent acts are executed; or else, a failure response is returned.
At acts S208-S210, the ProSe functional entity initiates the authorization process to the ProSe application server. Through the process, the ProSe functional entity can obtain a ProSe discovery identifier of the terminal. After the authorization is successfully completed, the ProSe functional entity allocates a ProSe code used for terminal announcement for the terminal.
In a roaming scenario, the home ProSe functional entity may acquire, through the above acts, Public Land Mobile Network (PLMN) information of a visited location where the terminal is currently registered, and then sends an announcement authorization request to the ProSe of the visited location after S208 to S210, where the announcement authorization request may carry parameters such as the ProSe code, a period of validity and a restrained ProSe application identifier.
At act S212, the ProSe functional entity returns an announcement response to the announcing terminal, where the announcement response may carry the ProSe code and the period of validity of the terminal.
At act S214, the terminal announces the received ProSe code.
At act S216, if a certain monitoring terminal hopes to monitor announcement information of its friend, the monitoring terminal sends to the ProSe application server an application layer ID of the terminal that the monitoring terminal expects to monitor. The ProSe application server returns to the monitoring terminal the restrained ProSe application identifier of the terminal that the monitoring terminal expects to monitor.
At act S218, the monitoring terminal sends a monitoring request to a home network ProSe functional entity, where the monitoring request may carry the restrained ProSe application identifier of the monitoring terminal and a container that may be transparently transferred to the ProSe application server, the container containing the restrained ProSe application identifier of the terminal that the monitoring terminal expects to monitor.
At act S220, if the ProSe functional entity does not have the context of the UE, it may be suggested to initiate the authorization process to the HSS, so as to obtain the ProSe-related subscription data of the user. If the terminal is permitted to perform the monitoring process, the subsequent acts are executed; or else, a failure response is returned.
At acts S222-S224, the ProSe functional entity initiates the authorization process to the ProSe application server. Through the process, the ProSe functional entity may obtain the restrained ProSe application identifier and the ProSe discovery identifier of the terminal that the monitoring terminal expects to monitor.
At acts S226-S228, a ProSe functional entity of the monitoring terminal initiates a monitoring request to a ProSe functional entity of the announcing terminal to obtain the ProSe code of the announcing terminal. Optionally, the ProSe functional entity of the announcing terminal may perform the authorization process again at the ProSe application server, so as to verify the validity of monitoring. The ProSe functional entity of the announcing terminal returns the ProSe code of the announcing terminal or ProSe filter information to the ProSe functional entity of the monitoring terminal.
At act S230, the ProSe functional entity of the monitoring terminal returns the ProSe code of the announcing terminal, or information including, e.g., the ProSe filter information and the period of validity. The terminal may filter the monitored information at an air interface according to the received code or filter information, so as to find a friend of the terminal.
In the above process, the ProSe application server is in charge of maintaining a friend relationship of the terminals on the application layer. Only the terminals in the specific friend list can discover each other, but the friend list may change. However, the change of the friend list is not considered in the related ProSe discovery technology, and once the friend relationship changes, the terminal which is monitoring or announcing is likely to be influenced.
To sum up, privacy of terminals cannot be ensured when a friend relationship between the terminals changes.